A recent survey by the Computer Security Institute and the San Francisco FBI's Computer Intrusion Squad revealed two very interesting trends when put side by side. Number one, virus attacks are the leading cause of financial losses among cyber crimes committed against U.S. companies. Number two, 98 percent of the companies and organizations polled for the survey say they use firewalls. Ninety-seven percent use antivirus software.

Virus attacks happen

There's plenty of preventative advice available to protect business owners from a virus attack and even more security products to purchase. But small businesses, in particular, would be wise to also have a crisis plan in place for what some would argue is inevitable.

"Small businesses are more vulnerable to attack," says Ben Rothke, director of security technology implementation at AXA Financial, a New York-based financial services firm, and the author of Computer Security -- 20 Things Every Employee Should Know. Small and mid-size businesses "typically don't have an IT department monitoring their network 24/7."

Signs of a possible virus attack

So what can a company without an IT department do to prepare for the worst? For starters, know enough about viruses to know when the system's been hit.

Computers start crashing all around the office at the same time.

One or more computers get flooded with pop-up ads.

One or more computers get multiple warning screens from your security software.

One or more computers get flooded with strange e-mails that seem to be replicating faster than they can be deleted.

The company network slows down to near-standstill.

Users are denied access when trying to log in.

Respond immediately

Once it's been determined the network's been attacked, you need to react. "Simply put, responding to a virus is like fighting a fire," says Devin Jopp, chief technology officer for SCORE, a counseling service for small business owners. Here are some tips for hot to respond to a virus attack.

Isolate Shut down all the infected computers and programs that appear to be infected to staunch the spread elsewhere within the network. As an added precaution, Joern Wettern, co-author of Firewalls for Dummies, says "disconnect any part of the system that is critical to your business… it helps to have those areas flagged in advance."

Treat Run your antivirus software. Jopp points out that 90 percent of all viruses can be identified and cleaned up by most antivirus programs.

Diagnose In addition to identifying the virus, assess what parts of the network have been hit, the damage inflicted and what it will take to fix it. For more complicated attacks, have a local IT consultant with expertise in cleaning up viruses that can be called in on short notice. "A virus attack on a small business is too critical to let the fix-it guy in the office handle on his own" says Rothke.

Learn See this as an opportunity to improve security for the next time. Chances are there's room for improvement by way of updating software more frequently or training employees to avoid high risk web sites or dubious e-mail, for example.

Don't forget the customers

Michael Shaw, California's assistant state director for the National Federation of Independent Business (NFIB) advocates full disclosure to customers in the event of a virus attack. "Employers need to have a plan in place to notify customers in case there is an attack that compromises customer information," he says. In a growing number of states, companies are required by law to report data breaches to customers.

Either way, a business owner may be wise to remember that a lost reputation is much harder to replace than lost data.